1. Field of the Invention
The present invention relates to an optical cameras and more particularly to an optical system of a zoom-camera in which a plural lens groups are arranged such that a path of light can be multi-directionally refracted in the zoom-camera.
2. Description of the Related Art
Typically, a camera is an optical apparatus for taking a photograph and is also referred to as a photographic machine. Beyond ordinary photographs, news photographs, commercial photographs, building photographs, microphotographs, aerial photographs, and astronomical photographs are widely used in various fields such as medical, industrial, scientific application, etc.
Cameras, as referred to herein, are classified as an ordinary camera which employs a film or more recently, a digital camera which does not require film.
An ordinary camera module is a device for receiving light to render an image to be formed on a film, wherein the camera module comprises a lens group for receiving and rendering light reflected from an object to be focused on a surface of a film, an iris for controlling the intensity of light incident into the camera module through the lens group, a focusing device for adjusting the distance between a lens and the film surface so that the image of the object can be clearly formed on the film surface, a film feeder for feeding films at a predetermined interval, and a shutter assembly for adjusting the length of time for exposing the film to the light.
The digital camera is similar to the ordinary camera module in construction. However, the digital camera is capable of storing a photographed image in an internal memory device (a hard disc or a memory card) instead of a film and the digital camera is capable of inputting a digital image into an external computer.
Here, the most significant component in each of the cameras is a lens. A simple camera may employ a convex meniscus lens or a plastic lens. However, most cameras employ two three or more lens groups. When such camera lens groups are employed in a camera, it is also possible to render magnifying power, thereby implementing a zoom function. In this case, the focal distance of a lens is made variable.
Zoom lenses known in the art are typically configured in a two-group type of positive and negative and a three-group type of positive, positive and negative, or negative, positive and negative.
The two-group type zoom lens implements the zoom function by adjusting the interval between the two lens groups, in which an optical tube and a driving device are simplified because the driving device can be provided by a minimum number of components.
Because the movement of each component group, accompanied at the time of zooming, is increased, the variation of aberration is further increased. Hence, it is known in the art that the two-group type zoom lens is not suitable for a high magnifying power.
The three-group type zoom lens is arranged in such a manner that the movement of each lens group, at the time of zooming, is limited and the variation of aberration can be well corrected. Hence, the three-group type zoom lens is suitable for a high magnifying power. However, there is a disadvantage in the three-group type zoom lens in that because an optical tube and a driving device are complicated and large in size due to the increased number of the lens groups. Hence, the size of a final product is increased. Thereby precluding the miniaturization and thinning of the final product.
In addition, as shown in FIGS. 1 and 2, a lens group 1 of the two-group or three-group type usually employs a prism 2 or a mirror 3 to change the path of a light 4 ninety degrees so that the light progresses in one direction to form an image in an image sensor 5. Such a zooming method is called an inner focus method.
However, this zooming method has a problem in that because lens groups of each type are arranged in a line to cause the path of light to progress in one direction and a driving device moves the lens groups in this state, the driving device is too large and it is difficult to install the driving device although the zooming method may somewhat miniaturize such a camera module. In addition, there is also a problem in that because a space is additionally required for the driving device, it is difficult to provide those lens groups for a portable terminal or a small-sized camera.